T. N. Ukwatta (GWU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. K. Cannizzo (NASA/UMBC),J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC), (i.e. the Swift-BAT team):

Using the data set from T-130 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 100728A (trigger #430151) (Cannizzo, et al., GCN 11004). The BAT ground-calculated position is RA, Dec = 88.753, -15.259 deg which is RA(J2000) = 05h 55m 00.7s Dec(J2000) = -15d 15' 33.0" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 81%. The BAT light curve is quite complex with a long series of peaks and flares extending from approximately T-100 sec to T+750 sec. Detected emission began around T-100 sec, rising to a first peak at T-40 sec. The burst continued as a series of at least ten overlapping peaks with the strongest peak centered at T+30 sec. There was a strong set of BAT peaks centered at T+120 sec, corresponding with the second flare detected by the XRT (Evans & Cannizzo, GCN 11014). This was followed by a series of weaker flares out to T+750 sec, at times which appear to correspond to flares detected by the XRT. The burst triggered just after the spacecraft settled following a slew to a pre-planned target, so it is possible that there was some very early emission (before T-120 sec) which was not detected. T90 (15-350 keV) is 198.5 +- 12.7 sec (estimated error including systematics). The time-averaged spectrum from T-84.3 to T+334.0 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.18 +- 0.02. The fluence in the 15-150 keV band is 3.8 +- 0.0 x 10^-5 erg/cm2. The 1-sec peak photon flux measured from T+28.26 sec in the 15-150 keV band is 5.1 +- 0.2 ph/cm^2/sec. All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/430151/BA/

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